The present invention relates to a recording apparatus for printing print data including image data by jetting an ink droplet from a nozzle opening while displacing a pressure producing chamber using a piezoelectric vibrating element.
As personal computers are gaining in popularity and graphics data processing technology is improving, production of high quality hard copies not only in terms of character data but also for graphics images is becoming increasingly important.
While thermal printers can print such data at a high dot density and tone, these printers entail high operating costs due to expensive ink ribbons the like. To overcome this problem, ink jet printers, whose operating costs are lower, are often used.
However, in the case of printing, for example, a so-called solid image that covers all or a large portion of the surface of the recording paper, a process involving wetting the entire surface of the recording paper with ink must be employed. As a result, the hard copy tends to wrinkle and takes a long time to dry. Further, in the case of printing a color image, the size of the ink droplets ejected from the recording head must be changed to express density gradations.
A technique for changing the size of the ejected ink droplets is described in Japanese Patent Unexamined Publication No. Hei. 2-6137. That is, the size of an ink droplet is changed by adjusting the maximum or minimum voltage applied to a pressure producing element. According to this drive method, ink droplets of different sizes are ejected by changing the volume of the contracted pressure producing chamber at the time of ejecting the ink droplets, and the volume is returned to the initial condition thereafter. As a result, the meniscus and the vibration of the pressure producing element after the ink droplet has been ejected differ from one ejection operation to another, thereby impairing the print quality due to the ejection of tiny ink droplets after the main ink droplet has been ejected.